System, medium, and method of encoding/decoding multi-channel audio signals

ABSTRACT

An system, method, and method of encoding/decoding a multi-channel audio signal, including a decoding level generation unit producing decoding-level information that helps a bitstream including a number of audio channel signals and space information to be decoded into a number of audio channel signals, wherein the space information includes information about magnitude differences and/or similarities between channels, and an audio decoder decoding the bitstream according to the decoding-level information. Accordingly, even a single input bitstream can be decoded into a suitable number of channels depending on the type of a speaker configuration used. Scalable channel decoding can be achieved by partially decoding an input bitstream. In the scalable channel decoding, a decoder may set decoding levels and outputs audio channel signals according to the decoding levels, thereby reducing decoding complexity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/599,147 filed on Aug. 30, 2012 which is a continuation of applicationSer. No. 11/602,278 now U.S. Pat. No. 8,280,538 filed on Nov. 21, 2006,which claims the priority of Korean Patent Application No.10-2006-0030249, filed on Apr. 3, 2006, in the Korean IntellectualProperty Office, and the benefit of U.S. Provisional Patent ApplicationNo. 60/738,049, filed on Nov. 21, 2005, in the U.S. Patent and TrademarkOffice, the disclosures of which are incorporated herein in theirentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An embodiment of the present invention relates to the encoding and/ordecoding of audio signals, and more particularly, to a system, medium,and method encoding/decoding a multi-channel audio signal.

2. Description of the Related Art

Examples of a general audio coding include a waveform multi-channelaudio coding and a parametric multi-channel audio coding. In thewaveform multi-channel audio coding, 5 audio channel signals may bereceived and 5 audio channel signals may be output. Examples of thewaveform multi-channel audio coding include an MPEG-2 MC audio coding,an AAC MC audio coding, and a BSAC/AVS MC audio coding, for example. TheMPEG-2 MC audio coding is executed in two types of modes, one of whichis a mode operated on original signals and the other is a mode operatedon two downmixed signals and other independent signals, the AAC MC audiocoding is executed on original signals with PCE and default settings,and the BSAC/AVS MC is a bit sliced arithmetic audio coding executed onoriginal signals with channel_configuration_idx.

An example of the parametric multi-channel audio coding includes an MPEGsurround coding that decodes 1 or 2 input channel signals into 5 or 6channel signals. In addition, the MPEG surround coding is based on QuantMatrix Extention (QMF), a reverse one-input to two-output decoding tool(R-OTT), a reverse two-input to three-output decoding tool (R-TTT), anda R-OTT tree regarding extended signals. Here, as an example, aone-input to two-output tool is a tool that takes one input andgenerates two outputs.

FIG. 1 illustrates such an MPEG surround decoder. There are variousspeaker configurations at the receiver sides of decoders, for example,1, 2, 3 (front)/0(rear), 3/1, 3/2, and 5/2. Hence, the input encodedaudio bitstream can be decoded into all available audio channel signalswhich can be selectively chosen for output depending on the speakerconfiguration used at the receiver side of a decoder.

Similarly, FIG. 2 illustrates a corresponding encoder for encoding theinput audio channel signal into the audio bitstream and a decoder fordecoding the encoded audio channel signal. In the case of MPEG surround,the encoder encodes M input audio channel signals and outputs N audiochannel signals, as the audio bistream, with M being greater than N. Thedecoder may then decode the N encoded audio channel signals and output Ldecoded audio channel signals, with L being greater than or equal to N,and M being greater than or equal to L.

However, in such conventional decoders, the L audio channel signals aredirectly generated by decoding M input audio channel signals (e.g., whenM=N=L) or by an upmixing of downmixed M input audio channel signals intoN audio channel signals and then decoding the N audio channel signals.However, it is difficult to decode input audio channel signals intoaudio signals of a suitable number of channels based on the actual knowntype of a speaker configuration at the receiver.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a system, medium, andmethod of encoding/decoding a multi-channel audio signal, by which inputaudio channel signals are selectively decoded into audio signals of asuitable number of channels depending on the type of speakerconfiguration at the receiver side of the decoder based on a selectivelevel of decoding.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be apparentfrom the description, or may be learned by practice of the invention.

To achieve at least the above and/or other aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding system, including a decoding level generation unit togenerate decoding-level information to control a level of decoding of abitstream having a predetermined number N of encoded audio channelsignals and space information into a number L (where L≧N) of audiochannel signals, wherein the space information includes information ofmagnitude differences and/or similarities between correspondingchannels, and an audio decoder to selectively decode, through differentlevels of decoding, the bitstream based on the decoding-levelinformation and to generate the number L of audio channel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding method, including selectively decoding a bitstream basedupon decoding-level information to control a level of decoding of thebitstream having a predetermined number N of encoded audio channelsignals and space information into a number L of audio channel signals,wherein the space information includes information of magnitudedifferences and/or a similarities between corresponding channels.

To achieve at least the above and/or still further aspects andadvantages, embodiments of the present invention include a multi-channelaudio signal decoding system, including a first OTT decoder to decode asingle audio channel signal and space information, with a correspondingbitstream including a corresponding encoded single audio channel signal,into two audio channel signals, wherein the space information includesinformation of magnitude differences and/or similarities betweencorresponding channels, a TTT decoder to decode the two audio channelsignals into three audio channel signals, as first, second, and thirdchannel signals, a second OTT decoder to decode the first channel signalinto a first plural channel signals, a third OTT decoder to decode thesecond channel signal into a second plural channel signals, and a fourthOTT decoder to decode the third channel signal into a third pluralchannel signals.

To achieve at least the above and/or other aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding method, including a first OTT decoding of a single audiochannel signal and space information, with a corresponding bitstreamincluding a corresponding encoded single audio channel signal, into twoaudio channel signals, wherein the space information includesinformation of magnitude differences and/or similarities betweencorresponding channels, a TTT decoding of the two audio channel signalsobtained in the first OTT decoding into three audio channel signals, asfirst, second, and third channel signals, a second OTT decoding of thefirst channel signal into a first plural channel signals, a third OTTdecoding of the second channel signal into a second plural channelsignals, and a fourth OTT decoding of the third channel signal into athird plural channel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding system, including a TTT decoder to decode two audiochannel signals and space information, with a corresponding bitstreamincluding corresponding two encoded audio channel signals, into threeaudio channel signals, as first, second, and third channel signals,wherein the space information includes information of magnitudedifferences and/or similarities between corresponding channels, a firstOTT decoder to decode the first channel signal into a first pluralchannel signals, a second OTT decoder to decode the second channelsignal into a second plural channel signals, a third OTT decoder todecode the third channel signal into a third plural channel signals, afourth OTT decoder to decode one of the first plural channel signalsoutput by the first OTT decoder into a fourth plural channel signals,and a fifth OTT decoder to decode one of the second plural channelsignals output by the second OTT decoder into a fifth plural channelsignals.

To achieve at least the above and/or still further aspects andadvantages, embodiments of the present invention include a multi-channelaudio signal decoding method, including a TTT decoding of two audiochannel signals and space information, with a corresponding bitstreamincludes corresponding two encoded audio channel signals, into threeaudio channel signals, as first, second, and third channel signals,wherein the space information includes information of magnitudedifferences and/or similarities between corresponding channels, a firstOTT decoding of the first channel signal into a first plural channelsignals, a second OTT decoding of the second channel signal into asecond plural channel signals, a third OTT decoding of the third channelsignal into a third plural channel signals, a fourth OTT decoding of oneof the first plural channel signals output in the first OTT decodinginto a fourth plural channel signals, and a fifth OTT decoding of one ofthe second plural channel signals output in the second OTT decoding intoa fifth plural channel signals.

To achieve at least the above and/or other aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding system, including a TTT decoder decoding two audiochannel signals and space information, with a corresponding bitstreamincluding corresponding two encoded audio channel signals, into threeaudio channel signals, as first, second, and third channel signals,wherein the space information includes information of magnitudedifferences and/or similarities between corresponding channels, a firstOTT decoder to decode the first channel signal into a first pluralchannel signals, a second OTT decoder to decode the second channelsignal into a second plural channel signals, a third OTT decoder todecode the third channel signal into a third plural channel signals, afourth OTT decoder to decode one of the third plural channel signals ofthe third OTT decoder into a fourth plural channel signals, a fifth OTTdecoder to decode one of the fourth plural channel signals of the fourthOTT decoder into the fifth plural channel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding method, including a TTT decoding of two audio channelsignals and space information, with a corresponding bitstream includingcorresponding two encoded audio channel signals, into three audiochannel signals, as first, second, and third channel signals, whereinthe space information includes information of magnitude differencesand/or similarities between corresponding channels, a first OTT decodingof the first channel signal into a first plural channel signals, asecond OTT decoding of the second channel signal into a second pluralchannel signals, a third OTT decoding of the third channel signal into athird plural channel signals, a fourth OTT decoding of one of thirdplural channel signals output in the third deocding into a fourth pluralchannel signals, and a fifth OTT decoding of one of fourth pluralchannel signals output in the fourth OTT decoding into a fifth pluralchannel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding system, including a first OTT decoder to decode abitstream including two encoded audio channel signals, as first andsecond audio channel signals, and space information so that the firstaudio channel signal is decoded into a first plural audio channelsignals, wherein the space information includes information of magnitudedifferences and/or similarities between corresponding channels, a secondOTT decoder to decode the second audio channel signal into a secondplural audio channel signals, as first and second channel signals, athird OTT decoder to decode one of the first plural channel signalsoutput by the first OTT decoder into a third plural channel signals, afourth OTT decoder to decode the first channel signal into a fourthplural channel signals, a fifth OTT decoder to decode the second channelsignal into a fifth plural channel signals, and a sixth OTT decoder todecode another of the first plural channel signals of the first OTTdecoder into a sixth plural channel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal decoding method including a first OTT decoding of a bitstreamincluding two encoded audio channel signals, as a first audio channelsignal and a second audio channel signal, and space information so thatthe first audio channel signal is decoded into a first plural audiochannel signals, wherein the space information includes information ofmagnitude differences and/or similarities between correspondingchannels, a second OTT decoding of the second audio channel signal intoa second plural audio channel signals, as first and second channelsignals, a third OTT decoding of one of the first plural channel signalsobtained in the first OTT decoding into a third plural channel signals,a fourth OTT decoding of the first channel signal into a fourth pluralaudio channel signals, a fifth OTT decoding of the second channel signalinto a fifth plural audio channel signals, and a sixth OTT decodinganother of the first plural audio channel signals obtained in the firstOTT decoding into a sixth plural channel signals.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding system, including a first OTT encoder to generate afirst OTT audio channel (L) signal and a first OTT parameter from a leftfront audio channel (LF) signal and a left surround audio channel (LS)signal, wherein the first OTT parameter includes information ofmagnitude differences and/or similarities between corresponding LF andLS channels, a second OTT encoder to generate a second OTT audio channel(R′) signal and a second OTT parameter from a right front audio channel(RF) signal and a right surround audio channel (RS) signal, wherein thesecond OTT parameter includes information of magnitude differencesand/or similarities between corresponding RF and RS channels, third OTTencoder to generate a third OTT audio channel (C′) signal and a thirdOTT parameter from a center audio channel (C) signal and a woofer audiochannel (LFE) signal, wherein the third OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding C and LFE channels, a TTT encoder to generate plural TTTaudio channel signals and a TTT parameter from the L′, R′, and C′channel signals output by the first, second, and third OTT encoders,respectively, wherein the TTT parameter includes information ofmagnitude differences and/or similarities between corresponding L′, R′,and C′ channels, a fourth OTT encoder to generate a fourth OTT audiochannel signal and a fourth OTT parameter from the plural TTT audiochannel signals output by the TTT encoder, wherein the fourth OTTparameter includes information of magnitude differences and/orsimilarities between corresponding plural TTT channels, a bitstreamgeneration unit to compress the OTT parameters generated by the firstthrough fourth OTT encoders, the TTT parameter generated by the TTTencoder, and the fourth OTT audio signal generated by the fourth OTTencoder so as to generate a bitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding system, including a first OTT encoder to generate afirst OTT audio channel (FL′) signal and a first OTT parameter from afront left audio channel (FL) signal and a front left center audiochannel (FLC) signal, wherein the first OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FL and FLC channels, a second OTT encoder to generate asecond OTT audio channel (FR′) signal and a second OTT parameter from afront right audio channel (FR) signal and a front right center audiochannel (FRC) signal, wherein the second OTT parameter includesinformation of magnitude differences and/or a similarities betweencorresponding FR and FRC channels, a third OTT encoder to generate athird OTT audio channel (L) signal and a third OTT parameter from theaudio channel (FL′) signal produced by the first OTT encoder and a backleft audio channel (BL) signal, wherein the third OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FL′ and BL channels, a fourth OTT encoder to generate afourth OTT audio channel (R′) signal and a fourth OTT parameter from theaudio channel (FR′) signal produced by the second OTT encoder and a backright audio channel (BR) signal, wherein the fourth OTT parameterincludes information of magnitude differences and/or similaritiesbetween corresponding FR′ and BR channels, a fifth OTT encoder togenerate a fifth OTT audio channel (C′) signal and a fifth OTT parameterfrom a center audio channel (C) signal and a woofer audio channel (LFE)signal, wherein the fifth OTT parameter includes information ofmagnitude differences and/or similarities between corresponding C andLFE channels, a TTT encoder producing plural TTT audio channel signalsand a TTT parameter from the L′, R′, and C′ channel signals output bythe third, fourth, and fifth OTT encoders, respectively, wherein the TTTparameter includes information of magnitude differences and/orsimilarities between corresponding L′, R′, and C′ channels, and abitstream generation unit to compress the parameters generated by thefirst through fifth OTT encoders and the TTT encoder and the plural TTTaudio signals generated by the TTT encoder so as to generate abitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding system, including a first OTT encoder to generate afirst OTT audio channel (FC′) signal and a first OTT parameter from afront left center audio channel (FLC) signal and a front right centeraudio channel (FRC) signal, wherein the first OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FLC and FRC channels, a second OTT encoder to generate asecond OTT audio channel (C′) signal and a second OTT parameter from theaudio channel (FC′) signal output by the first OTT encoder and a centeraudio channel (C) signal, wherein the second OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FC′ and C channels, a third OTT encoder to generate athird OTT audio channel (L′) signal and a third OTT parameter from afront left audio channel (FL) signal and a back left audio channel (BL)signal, wherein the third OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FL andBL channels, a fourth OTT encoder to generate a fourth OTT audio channel(R′) signal and a fourth OTT parameter from an audio channel (FR) signaland a back right audio channel (BR) signal, wherein the fourth OTTparameter includes information of magnitude differences and/orsimilarities between corresponding FR and BR channels, a fifth OTTencoder to generate a fifth OTT audio channel (C′) signal and a fifthOTT parameter from the audio channel (C′) signal output by the secondOTT encoder and a woofer audio channel (LFE) signal, wherein the fifthOTT parameter includes information of magnitude differences and/orsimilarities between corresponding C′ and LFE channels, a TTT encoder togenerate plural TTT audio channel signals and a TTT parameter from theL′, R′, and C′ channel signals output by the third, fourth, and fifthOTT encoders, respectively, wherein the TTT parameter includesinformation of magnitude differences and/or similarities between the L′,R′, and C′ channels, and a bitstream generation unit to compress theparameters generated by the first through fifth OTT encoders and the TTTencoder and the plural TTT audio channel signals generated by the TTTencoder so as to generate a bitstream.

To achieve at least the above and/or still further aspects andadvantages, embodiments of the present invention include a multi-channelaudio signal encoding system, including a first OTT encoder to generatea first OTT audio channel (C′) signal and a first OTT parameter from afront left center audio channel (FLC) signal and a front right centeraudio channel (FRC) signal, wherein the first OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FLC and FRC channels, a second OTT encoder to generate asecond OTT audio channel (L′) signal and a second OTT parameter from afront left audio channel (FL) signal and a back left audio channel (BL)signal, wherein the second OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FL andBL channels, a third OTT encoder to generate a third OTT audio channel(R′) signal and a third OTT parameter from a front right audio channel(FR) signal and a back right audio channel (BR) signal, wherein thethird OTT parameter includes information of magnitude differences and/orsimilarities between corresponding FR and BR channels, a fourth OTTencoder to generate a fourth OTT audio channel (C′) signal and a fourthOTT parameter from a center audio channel (C) signal and a woofer audiochannel (LFE) signal, wherein the fourth OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding C and LFE channels, a fifth OTT encoder to generate afifth OTT audio channel signal and a fifth OTT parameter from the audiochannel (L′) signal output by the second OTT encoder and the audiochannel (C′) signal output by the first OTT encoder, wherein the fifthOTT parameter includes information of magnitude differences and/orsimilarities between corresponding L′ and C′ channels, a sixth OTTencoder to generate a sixth OTT audio channel signal and a sixth OTTparameter from the audio channel (R′) signal output by the third OTTencoder and the audio channel (C′) signal output by the fourth OTTencoder, wherein the sixth OTT parameter includes information ofmagnitude differences and/or similarities between corresponding R′ andC′ channels, and a bitstream generation unit to compress the parametersgenerated by the first through sixth OTT encoders, the fifth OTT audiochannel signal generated by the fifth OTT encoder, and the sixth OTTaudio channel signal generated by the sixth OTT encoder so as togenerate a bitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding method, including a first OTT encoding of a first OTTparameter and a first OTT audio channel (L) signal from a left frontaudio channel (LF) signal and a left surround audio channel (LS) signal,wherein the first OTT parameter includes information of magnitudedifferences and/or similarities between corresponding LF and LSchannels, a second OTT encoding of a second OTT parameter and a secondOTT audio channel (R′) signal from a right front audio channel (RF)signal and a right surround audio channel (RS) signal, wherein thesecond OTT parameter includes information of magnitude differencesand/or similarities between corresponding RF and RS channels, a thirdOTT encoding of a third OTT parameter and a third OTT audio channel (C′)signal from a center audio channel (C) signal and a woofer audio channel(LFE) signal, wherein the third OTT parameter includes information ofmagnitude differences and/or similarities between corresponding C andLFE channels, a TTT encoding of a TTT parameter and plural TTT audiochannel signals from the L′, R′, and C channel signals produced in thefirst, second, and third OTT encodings respectively, wherein the TTTparameter includes information of magnitude differences and/orsimilarities between corresponding L′, R′, and C channels, a fourth OTTencoding of a fourth OTT parameter and a fourth OTT audio channel signalfrom the plural TTT audio channel signals generated in the TTT encoding,compressing the parameters generated in the first through fourth OTTencodings and the TTT encoding and the fourth OTT audio channel signalencoded in the fourth OTT encoding so as to generate a bitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding method, including a first OTT encoding of a first OTTaudio channel (FL′) signal and a first OTT parameter from a front leftaudio channel (FL) signal and a front left center audio channel (FLC)signal, wherein the first OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FL andFLC channels, a second OTT encoding of a second OTT audio channel (FR′)signal and a second OTT parameter from a front right audio channel (FR)signal and a front right center audio channel (FRC) signal, wherein thesecond OTT parameter includes information of magnitude differencesand/or similarities between corresponding FR and FRC channels, a thirdOTT encoding of a third OTT audio channel (L) signal and a third OTTparameter from the front left audio channel (FL′) signal generated inthe first OTT encoding and a back left audio channel (BL) signal,wherein the third OTT parameter includes information of magnitudedifferences and/or similarities between corresponding FL′ and BLchannels, a fourth OTT encoding of a fourth OTT audio channel (R′)signal and a fourth OTT parameter from the front right audio channel(FR′) signal generated in the second OTT encoding and a back right audiochannel (BR) signal, wherein the fourth OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FR′ and BR channels, a fifth OTT encoding of a fifth OTTaudio channel (C′) signal and a fifth OTT parameter from a center audiochannel (C) signal and a woofer audio channel (LFE) signal, wherein thefifth OTT parameter includes information of magnitude differences and/orsimilarities between corresponding C and LFE channels, a TTT encoding ofplural TTT (stereo) audio channel signals and a TTT parameter from theL′, R′, and C′ channel signals generated in the third, fourth, and fifthOTT encodings, respectively, wherein the TTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding L′, R′, and C′ channels, compressing the parametersgenerated in the first through fifth OTT encodings and the plural stereoaudio channel signals generated in the TTT encoding so as to generate abitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding method, including a first OTT encoding of a first OTTaudio channel (FC′) signal and a first OTT parameter from a front leftcenter audio channel (FLC) signal and a front right center audio channel(FRC) signal, wherein the first OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FLC andFRC channels, a second OTT encoding of a second OTT audio channel (C′)signal and a second OTT parameter from the audio channel (FC′) signalgenerated in the first OTT encoding and a center audio channel (C)signal, wherein the second OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FC′ andC channels, a third OTT encoding of a third OTT audio channel (L) signaland a third OTT parameter from a front left audio channel (FL) signaland a back left audio channel (BL) signal, wherein the third OTTparameter includes information of magnitude differences and/orsimilarities between corresponding FL and BL channels, a fourth OTTencoding of a fourth OTT audio channel (R′) signal and a fourth OTTparameter from a front right audio channel (FR) signal and a back rightaudio channel (BR) signal, wherein the fourth OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FR and BR channels, a fifth OTT encoding of a fifth OTTaudio channel (C′) signal and a fifth OTT parameter from the audiochannel (C′) signal generated in the second OTT encoding and a wooferaudio channel (LFE) signal, wherein the fifth OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding C′ and LFE channels, a TTT encoding of plural TTT (stereo)audio channel signals and a TTT parameter from the L′, R′, and C′channel signals generated in the third, fourth, and fifth OTT encodings,respectively, wherein the TTT parameter includes information ofmagnitude differences and/or similarities between corresponding L′, R′,and C′ channels, compressing the parameters generated in the firstthrough fifth OTT encodings and the audio channel signals generated inthe TTT encoding so as to generate a bitstream.

To achieve at least the above and/or further aspects and advantages,embodiments of the present invention include a multi-channel audiosignal encoding method, including a first OTT encoding of a first OTTaudio channel (C′) signal and a first OTT parameter from a front leftcenter audio channel (FLC) signal and a front right center audio channel(FRC) signal, wherein the first OTT parameter includes information ofmagnitude differences and/or similarities between corresponding FLC andFRC channels, a second OTT encoding of a second OTT audio channel (L′)signal and a second OTT parameter from a front left audio channel (FL)signal and a back left audio channel (BL) signal, wherein the second OTTparameter includes information of magnitude differences and/orsimilarities between corresponding FL and BL channels, a third OTTencoding of a third OTT audio channel (R′) signal and a third OTTparameter from a front right audio channel (FR) signal and a back rightaudio channel (BR) signal, wherein the third OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding FR and BR channels, a fourth OTT encoding of a fourth OTTaudio channel (C″) signal and a fourth OTT parameter from a center audiochannel (C) signal and a woofer audio channel (LFE) signal, wherein thefourth OTT parameter includes information of magnitude differencesand/or similarities between corresponding C and LFE channels, a fifthOTT encoding of a fifth OTT audio channel signal and a fifth OTTparameter from the audio channel (L′) signal generated in the second OTTencoding and the audio channel (C′) signal generated in the first OTTencoding, wherein the fifth OTT parameter includes information ofmagnitude differences and/or similarities between corresponding L′ andC′ channels, a sixth OTT encoding of a sixth OTT audio channel signaland a sixth OTT parameter from the audio channel (R′) signal generatedin the first OTT encoding and the audio channel (C″) signal generated inthe fourth OTT encoding, wherein the sixth OTT parameter includesinformation of magnitude differences and/or similarities betweencorresponding R′ and C″ channels, and compressing the parametersgenerated in the first through sixth OTT encodings, the fifth OTT audiochannel signal generated in the fifth OTT encoding, and the sixth OTTaudio channel signal generated in the sixth OTT encoding so as togenerate a bitstream.

To achieve at least the above and/or still further aspects andadvantages, embodiments of the present invention include at least onemedium including computer readable code to control at least oneprocessing element to implement an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 illustrates a conventional MPEG surround decoder;

FIG. 2 illustrates a conventional encoder for encoding an input audiochannel signal, a resultant encoded audio channel signal bitstream, anda conventional decoder for decoding the encoded audio channel signal;

FIG. 3 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention;

FIG. 4 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention;

FIG. 5 illustrates a decoder for decoding a downmixed signal, such asdescribed in FIG. 4 by referring to various decoding levels, accordingto an embodiment of the present invention;

FIG. 6 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention;

FIG. 7 illustrates a multi-channel audio signal decoding method,according to another embodiment of the present invention;

FIG. 8 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention;

FIG. 9 illustrates a multi-channel audio signal decoding method,according to another embodiment of the present invention;

FIG. 10 illustrates a multi-channel audio signal decoding system,according to another embodiment of the present invention;

FIG. 11 illustrates a multi-channel audio signal decoding method,according to another embodiment of the present invention;

FIG. 12 illustrates a multi-channel audio signal decoding system,according to still another embodiment of the present invention;

FIG. 13 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention;

FIG. 14 illustrates a multi-channel audio signal encoding system,according to an embodiment of the present invention;

FIG. 15 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention;

FIG. 16 illustrates a multi-channel audio signal encoding system,according to another embodiment of the present invention;

FIG. 17 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention;

FIG. 18 illustrates a multi-channel audio signal encoding system,according to another embodiment of the present invention;

FIG. 19 illustrates a multi-channel audio signal encoding method,according to another embodiment of the present invention;

FIG. 20 illustrates a multi-channel audio signal encoding system,according to still another embodiment of the present invention; and

FIG. 21 illustrates a multi-channel audio signal encoding method,according to another embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. Embodiments are described below to explain the presentinvention by referring to the figures.

Hereinafter, according to differing embodiments of the presentinvention, even a single input bitstream can be selectively decoded intoaudio channel signals of a suitable number of channels based on the typeof receiver speaker configuration. Accordingly, scalable channeldecoding can be achieved by only partially decoding the input bitstream.In the scalable channel decoding, a decoder may set decoding levels,setting the level of decoding, and output audio channel signalsaccording to the decoding levels, thereby decreasing the decodingcomplexity.

FIG. 3 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention, which may includean audio decoder 300 and a decoding level generation unit 350, forexample. The decoding level generation unit 350 may produce decodinglevel information that helps in the decoding of a bitstream having apredetermined number N of audio channel signals and space informationinto a predetermined number L (where L≧N) of audio channel signals.Here, the space information may include information about magnitudedifferences and similarities between channels, during the correspondingencoding of the channels.

Thus, the audio decoder 300 may selectively decode the bitstreamaccording to such decoding level information and output the L audiochannel signals.

FIG. 4 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention. In operation 400,the decoding level information that may be used in the selectivedecoding of the bitstream, e.g., including the N audio channel signalsand the space information, into the L audio channel signals may beproduced. The bitstream may be a downmixed signal, e.g., a mono signal,included with the space information for eventual upmixing to additionalsignals through modification of the downmixed signal based upon thespace information. Here, as noted above, the bitstream may include thedownmixed signal and additional material, which may be variously calledspecial parameters or spatial cues, for example, with that additionalmaterial including information on how each upmixed signal differentiatesfrom either each other or from the downmixed mono signal. With thistechnique of sending only the downmixed signal and the additionalmaterial, substantial data volume can be reduced, e.g., with almost halfas much total data being sent for the downmixed mono signal compared todata required for each separate left and right example channels. Thus,further to above, FIG. 5 further illustrates a decoder decoding thedownmixed signal by referring to various decoding levels. Referencecharacters dl0, dl1, and dl2 denote such decoding levels, wherein dl0denotes a core decoding level. FIG. 5 illustrates a two-to-threedecoding tool (TTT) at the dl1 level, and one-to-two decoding tools(OTT) at the dl2 level. As an example, if the dl2 level is used fordecoding the downmixed signals, only the left (L′), right (R′), andcenter (C′) are decoded and output for a left, right, and center channelspeakers. Such operation is further discussed with the below referenceto FIG. 6.

Again, in FIG. 4, in operation 450, the bitstream may be decoded basedon the decoding levels to output the desired number of decoded audiochannel signals corresponding to the appropriate decoding level.

FIG. 6 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention, which may include afirst OTT decoder 600, a TTT decoder 610, a second OTT decoder 620, athird OTT decoder 630, and a fourth OTT decoder 640, for example. Themulti-channel audio signal decoding system may further include adecoding level generation unit 650, for example.

The first OTT decoder 600 decodes a bitstream including one audiochannel signal, e.g., a downmixed signal, and the aforementioned spaceinformation so that the single audio channel signal is upmixed andoutput as two audio channel signals. Here, the space information mayinclude magnitude differences between the channels, during thecorresponding encoding of the channels, and information aboutsimilarities between the same channels. The two audio channels output bythe first OTT decoder 600 may be considered stereo audio channels, e.g.,for selective output to left and right speakers if the dl1 level is usedin the decoding.

The TTT decoder 610 decodes the two audio channel signals into threeaudio channel signals. Here, the three channels of the three audiochannel signals output by the TTT decoder 610 may be considered a leftaudio channel L′, a right audio channel R′, and a center audio channelC′, for example.

When the three audio channels signals output by the TTT decoder 610 arereferred to as first, second, and third channel signal, the second OTTdecoder 620 may decode the first channel signal into two channelsignals. The two channels of the two channel signals may be considered aleft front audio channel LF and a left surround audio channel LS, forexample.

Similarly, the third OTT decoder 630 may decode the second channelsignal into two channel signals. The two channels of the two channelsignals may be considered a right front audio channel RF and a rightsurround audio channel RS, for example.

Again, the fourth OTT decoder 640 may decode the third channel signalinto two channel signals. The two channels of the two channel signalsmay be a center audio channel C and a woofer audio channel LFE, forexample.

In one embodiment, the decoding level generation unit 650 may producedecoding level information used in the selective decoding of thebitstream into a predetermined number of audio channel signals. Thedecoding level information may include a first decoding level dl0, asecond decoding level dl1, a third decoding level dl2, and a fourthdecoding level dl3, for example. The first decoding level dl0 may beused in the decoding of a bitstream, including one audio channel signal,to control the selection level of decoding the bitstream into one audiochannel signal for output. The second decoding level dl1 may be used inthe decoding of the bitstream, including the single audio channel signaloutput at the first decoding level dl0, to control the selection levelof decoding the bitstream into two audio channel signals. The thirddecoding level dl2 may be used in the decoding of the bitstream,including the two audio channel signals output at the second decodinglevel dl1, to control the selection level of decoding the bitstream intothree audio channel signals, e.g., L′, R′, and C′ channels. The fourthdecoding level dl3 may be used in the decoding of the bitstream,including the three audio channel signals, output at the third decodinglevel dl2 to control the selection level of decoding the bitstream intosignals of 5.1 audio channels LF, LS, RF, RS, C, and LFE, for example.

FIG. 7 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention. In operation 700, abitstream including a single audio channel signal and space information,e.g., including magnitude differences between channels and/orinformation about similarities between channels, is decoded so that thetwo audio channel signals are output. The two channels may be consideredstereo audio channels, for example.

In operation 720, the two audio channel signals, e.g., from operation700, may be decoded into three audio channel signals, with the threechannels of the three audio channels, e.g., output by the TTT decoder610, being considered the left audio channel L′, the right audio channelR′, and the center audio channel C′.

When the three audio channel signals, e.g., obtained in operation 720,are referred to as first, second, and third channel signal, each of thefirst, second, and third channel signals is decoded into two channelsignals, whereby 5.1 channel signals are output, in operation 740. Here,the two channels of the two channel signals into which the first channelis decoded may be considered left front audio channel LF and a leftsurround audio channel LS, the two channels of the two channel signalsinto which the second channel signal is decoded may be considered aright front audio channel RF and a right surround audio channel RS, andthe two channels of the two channel signals into which the third channelsignal is decoded may be considered a center audio channel C and awoofer audio channel LFE.

Thus, to achieve the decoding of the bitstream into a predeterminednumber of audio channel signals, decoding level information may beneeded. The decoding level information may include a first decodinglevel that may be used in the selective decoding of the bitstreamincluding one audio channel signal to be decoded into one audio channelsignal, a second decoding level information that may be used in theselective decoding of the bitstream including the single audio channelsignal output at the first decoding level to be decoded into two audiochannel signals, a third decoding level that may be used in theselective decoding of the bitstream including the two audio channelsignals output at the second decoding level to be decoded into threeaudio channel signals of the three channels L′, R′, and C′, and a fourthdecoding level that may be used in the selective decoding of thebitstream including the three audio channel signals output at the thirddecoding level to be decoded into signals of 5.1 audio channels LF, LS,RF, RS, C, and LFE, for example.

FIG. 8 illustrates a multi-channel audio signal decoding, systemaccording to an embodiment of the present invention, which may include aTTT decoder 800, a first OTT decoder 810, a second OTT decoder 820, athird OTT decoder 830, a fourth OTT decoder 840, and a fifth OTT decoder850, for example. The multi-channel audio signal decoding system mayfurther include a decoding level generation unit 860, also as anexample.

The TTT decoder 800 may decode a bitstream including two audio channelsignals and space information so that the two audio channel signals areoutput as three audio channel signals, for example. Here, the spaceinformation may include information about magnitude differences andsimilarities between channels, during the corresponding encoding of thechannels. The channels of the three audio channel signals output by theTTT decoder 800 may be considered a left audio channel L′, a right audiochannel R′, and a center audio channel C′, for example.

With the three audio channel signals output by the TTT decoder 800 beingreferred to as first, second, and third channel signal, the first OTTdecoder 810 decodes the first channel signal into two channel signals,with the two channels of the two channel signals being considered afront left audio channel FL′ and a back left audio channel BL.

The second OTT decoder 820 may decode the second channel signal into twoadditional channel signals, with these two channels of the two channelsignals being considered a front right audio channel FR′ and a backright audio channel BR.

The third OTT decoder 830 may decode the third channel signal into twofurther channel signals, with these two channels of the two channelsignals being considered a center audio channel C and a woofer audiochannel LFE.

The fourth OTT decoder 840 may further decode one of the output signalsof the first OTT decoder 810, that is, the signal of the front leftaudio channel FL′, into two further channel signals, with these twochannels of the two channel signals output by the fourth OTT decoder 840being considered a front left audio channel FL and a front left centeraudio channel FLC.

The fifth OTT decoder 850 may still further decode one of the outputsignal of the second OTT decoder 820, that is, the signal of the frontright audio channel FR′, into two further channel signals, with thesetwo channels of the two channel signals output by the fifth OTT decoder850 being considered a front right audio channel FR and a front rightcenter audio channel FRC.

The decoding level generation unit 860 may generate decoding levelinformation that may be used in the selective decoding of the bitstreaminto a predetermined number of audio channel signals. Here, the decodinglevel information may include a first decoding level dl0, a seconddecoding level dl1, a third decoding level dl2, and a fourth decodinglevel dl3, for example.

The first decoding level dl0 may be used in the selective decoding ofthe bitstream including two audio channel signals into two audio channelsignals. The second decoding level dl1 may be used in the selectivedecoding of the bitstream including the two audio channel signals outputat the first decoding level dl0 into signals of three audio channels L′,R′, and C′, for example. The third decoding level dl2 may be used in theselective decoding of the bitstream including the three audio channelsignals output at the second decoding level dl1 into signals of 5.1audio channels FL′, BL, FR′, BR, C, and LFE, for example.

The fourth decoding level dl3 may be used in the selective decoding ofthe FL′ channel signal into the signals of the two audio channels FL andFLC and the FR′ channel signal into the signals of the two audiochannels FR and FRC so that a total of 7.1 channel signals are output,for example.

FIG. 9 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention. In operation 900, abitstream including two audio channel signals and space information,which may include information about magnitude differences andsimilarities between the channels, during the corresponding encoding ofthe channels, is decoded so that the three audio channel signals areoutput. The three channels of the three audio channel signals may beconsidered the left audio channel L′, the right audio channel R′, andthe center audio channel C′, for example.

With the three audio channel signals obtained in operation 900 beingreferred to as first, second, and third channel signals, each of thefirst, second, and third channel signals may be further decoded into twoadditional channel signals so that 5.1 channel signals are output, inoperation 920. The two channels of the two channel signals into whichthe first channel signal is decoded may be considered the front leftaudio channel FL′ and the back left audio channel BL, the two channelsof the two channel signals into which the second channel signal isdecoded may be considered a front right audio channel FR′ and a backright audio channel BR, and the two channels of the two channel signalsinto which the third channel signal is decoded may be considered acenter audio channel C and a woofer audio channel LFE, for example.

In operation 940, each of the signals of two channels for the 5.1channels may be further decoded such that signals of 7.1 channels areoutput. The channels of a signal into which the two channel signals aredecoded in operation 940 may be considered the front left audio channelFL, the front left center audio channel FLC, the front right audiochannel FR, and the front right center audio channel FRC, for example.

To achieve the aforementioned decoding of a bitstream into apredetermined number of audio channel signals, decoding levelinformation generated by a decoder may be used, for example, so thataudio channel signals can be decoded and output based upon theappropriate decoding levels. The decoding level information may includethe first decoding level dl0, which may be used in the selectivedecoding of the bitstream including two audio channel signals into twoaudio channel signals, the second decoding level dl1, which may be usedin the selective decoding of the a bitstream including the two audiochannel signals output at the first decoding level dl0 into signals ofthe three audio channels L′, R′, and C′, the third decoding level dl2,which may be used in the selective decoding of the a bitstream includingthe three audio channel signals into signals of 5.1 audio channels LF,LS, RF, RS, C, and LFE, and the fourth decoding level dl3, which may beused in the selective decoding of the FL′ channel signal into thesignals of the two audio channels FL and FLC and the FR′ channel signalinto the signals of the two audio channels FR and FRC so that a total of7.1 channel signals are output, in this embodiment.

FIG. 10 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention, and may include aTTT decoder 1000, a first OTT decoder 1010, a second OTT decoder 1020, athird OTT decoder 1030, a fourth OTT decoder 1040, and a fifth OTTdecoder 1050, for example. The multi-channel audio signal decodingsystem may further include a decoding level generation unit 1060, forexample.

The TTT decoder 1000 may decode a bitstream including two audio channelsignals and space information so that the three audio channel signalsare output from two audio channel signals. Here, the space informationmay include information about magnitude differences and similaritiesbetween the channels, during the corresponding encoding of the channels.The channels of the three audio channel signals output by the TTTdecoder 1000 may be considered a left audio channel L′, a right audiochannel R′, and a center audio channel C′, for example.

With the three audio channel signals output by the TTT decoder 1000being referred to as first, second, and third channel signals, the firstOTT decoder 1010 may decode the first channel signal into two channelsignals. The two channels of the two channel signals may be considered afront left audio channel FL and a back left audio channel BL, forexample.

The second OTT decoder 1020 may decode the second channel signal intotwo channel signals, with these two channels of the two channel signalsbeing considered a front right audio channel FR and a back right audiochannel BR, for example.

Similarly, the third OTT decoder 1030 may decode the third channelsignal into two channel signals, with these two channels of the twochannel signals being considered a center audio channel C″ and a wooferaudio channel LFE, again as an example.

The fourth OTT decoder 1040 may further decode one of the output signalsof the third OTT decoder 1030, e.g., the signal of the center audiochannel C″, into two channel signals, with these two channels of the twochannel signals output by the fourth OTT decoder 1040 being considered afront center audio channel FC′ and a center audio channel C, forexample.

The fifth OTT decoder 1050 may still further decode one of the outputsignals of the fourth OTT decoder 1040, e.g., the FC′ channel signal,into two channel signals, with the two channels of the two channelsignals output by the fifth OTT decoder 1050 being considered a frontleft center audio channel FLC and a front right center audio channelFRC, for example.

In one embodiment, the decoding level generation unit 1060 may generatedecoding level information that may be used during the selectivedecoding of the bitstream into a predetermined number of audio channelsignals. The decoding level information may include a first decodinglevel dl0, a second decoding level dl1, a third decoding level dl2, anda fourth decoding level dl3, for example.

Here, the first decoding level dl0 may be used during the selectivedecoding of the bitstream including two audio channel signals to bedecoded into two audio channel signals, the second decoding level dl1may be used during the selective decoding of the bitstream including thetwo audio channel signals output at the first decoding level dl0 intosignals of three audio channels L′, R′, and C′, the third decoding leveldl2 may be used during the selective decoding of the bitstream includingthe three audio channel signals output at the second decoding level dl1into signals of 5.1 audio channels FL, BL, FR, BR, C″, and LFE, and thefourth decoding level dl3 may be used during the selective decoding ofthe FC′ channel signal into the two FLC and FRC channel signals so thata total of 7.1 channel signals are output.

FIG. 11 illustrating a multi-channel audio signal decoding method,according to an embodiment of the present invention. In operation 1100,a bitstream including two audio channel signals and space informationthat includes magnitude differences between the channels and informationabout similarities between channels is decoded so that the three audiochannel signals are output from two audio channel signals. The threechannels of the three audio channel signals may be considered the leftaudio channel L′, the right audio channel R′, and the center audiochannel C′, for example.

With the three audio channel signals obtained in operation 1100 beingreferred to as first, second, and third channel signals, each of thefirst, second, and third channel signals may be decoded into two channelsignals so that 5.1 channel signals are output, in operation 1120. Morespecifically, the two channels of the two channel signals into which thefirst channel signal is decoded may be considered the front left audiochannel FL and the back left audio channel BL, the two channels of thetwo channel signals into which the second channel signal is decoded maybe considered the front right audio channel FR and the back right audiochannel BR, and the two channels of the two channel signals into whichthe third channel signal is decoded may be considered the center audiochannel C″ and the woofer audio channel LFE.

In operation 1140, the signals of two channels of the 5.1 channelsoutput in operation 1120 may be further decoded into two channelsignals, with the channels of the two channel signals being consideredthe front center audio channel FC′ and the center audio channel C, forexample.

In operation 1160, one of the two channel signals output in operation1140, for example, may be decoded into two channel signals, whereby 7.1channel signals are output, with the channels of the two channel signalsbeing considered the front left center audio channel FLC and the frontright center audio channel FRC, for example.

Thus, according to this embodiment, to achieve such a selective decodingof the bitstream into a predetermined number of audio channel signals,decoding level information generated by a decoder may be used so thataudio channel signals are output based on the decoding levels. Thedecoding level information may include the first decoding level dl0,which may be used during the selective decoding of the bitstreamincluding two audio channel signals into two audio channel signals, thesecond decoding level dl1, which may be used during the selectivedecoding of the bitstream including the two audio channel signals outputat the first decoding level dl0 into signals of the three audio channelsL′, R′, and C′, the third decoding level dl2, which may be used duringthe selective decoding of the bitstream including the three audiochannel signals to be decoded into signals of 5.1 audio channels FL, BL,FR, BR, C″, and LFE, and the fourth decoding level dl3, which may beused during the selective decoding of the FC′ channel signal to bedecoded into the signals of the two audio channels FLC and FRC so that atotal of 7.1 channel signals are output.

FIG. 12 illustrates a multi-channel audio signal decoding system,according to an embodiment of the present invention, which may include afirst OTT decoder 1200, a second OTT decoder 1210, a third OTT decoder1220, a fourth OTT decoder 1230, a fifth OTT decoder 1240, and a sixthOTT decoder 1250, for example. The multi-channel audio signal decodingsystem may further include a decoding level generation unit 1260, in anembodiment.

In response to a bitstream including two audio channel signals, e.g.,first and second audio channel signals, and space information, the firstOTT decoder 1200 may decode the first audio channel signal into twoaudio channel signals. Here, the space information may includeinformation about magnitude differences between channels, during thecorresponding encoding of the channels, and similarities therebetween.The channels of the two audio channel signals output by the first OTTdecoder 1200 may be considered a left audio channel L and a center audiochannel C′, for example.

The second OTT decoder 1210 may decode the bitstream so that two audiochannel signals are output as the second audio channel signal. Thechannels of the two audio channel signals output by the second OTTdecoder 1210 may be considered a right audio channel R′ and a centeraudio channel C″.

The third OTT decoder 1220 may decode one of the two channel signalsoutput by the first OTT decoder 1200, e.g., the L′ channel signal, intotwo further channel signals. The two channels of the two channel signalsoutput by the third OTT decoder 1220 may be considered a front leftcenter audio channel FL and a back left audio channel BL, for example.

With the two audio channel signals output by the first OTT decoder 1210being referred to as first and second channel signals, the fourth OTTdecoder 1230 may decode the first channel signal into two channelsignals, with the two channels of the two channel signals beingconsidered a front right audio channel FR and a back right audio channelBR.

The fifth OTT decoder 1240 may decode the second channel signal into twochannel signals, with the two channels of the two channel signals beingconsidered a center audio channel C and a woofer audio channel LFE.

The sixth OTT decoder 1250 may decode the other of the two outputsignals of the first OTT decoder 1200, e.g., the C′ channel signal, intotwo channel signals, with the two channels of the two channel signalsoutput by the sixth OTT decoder 1250 being a front left center audiochannel FLC and a front right center audio channel FRC.

In an embodiment, the decoding level generation unit 1260 may generatedecoding level information that may be used in selective decoding of thebitstream into a predetermined number of audio channel signals. Thedecoding level information may include a first decoding level dl0, asecond decoding level dl1, a third decoding level dl2, and a fourthdecoding level dl3, for example.

Here, the first decoding level dl0 may be used during the selectivedecoding of the bitstream including two audio channel signals into twoaudio channel signals.

The second decoding level dl1 may be used during the selective decodingof the bitstream including the two audio channel signals output at thefirst decoding level dl0 into signals of four audio channels L′, C′, R′,and C′, for example.

The third decoding level dl2 may be used during the selective decodingof the L′ audio channel signal into signals of two audio channels FL andBL, the R′ audio channel signal to be decoded into signals of two audiochannels FR and BR, and the C″ audio channel signal to be decoded intosignals of two audio channels C and LFE, for example.

The fourth decoding level dl3 may be used during the selective decodingof the C″ channel signal into the two FLC and FRC channel signals.

FIG. 13 illustrates a multi-channel audio signal decoding method,according to an embodiment of the present invention. In operation 1300,a bitstream including two audio channel signals, e.g., a first audiochannel signal and a second audio channel signal, and space informationthat may includes information about magnitude differences between thechannels and similarities therebetween, during the correspondingencoding of the channels, is decoded so that the first audio channelsignal is output as two audio channel signals, e.g., L′ and C′ audiochannel signals. Here, L′ and C′ denote right and center audio channels,respectively. Also, in operation 1300, the bitstream may be decoded sothat the second audio channel signal is output as two audio channelsignals, e.g., R′ and C′ audio channel signals, with R′ and C″ denotingright and center audio channels, respectively.

In operation 1320, the L′ signal obtained in operation 1300 may bedecoded into signals of the front left audio channel FL and the backleft audio channel BL.

In operation 1340, the first channel signal may be decoded into thefront right audio channel (FR) signal and the back right audio channel(BR) signal. In operation 1360, the second channel (C″) signal may bedecoded into the center audio channel (C) signal and the woofer audiochannel (LFE) signal. Further, in operation 1380, the C″channel signalobtained in operation 1300 may be decoded into the front left centeraudio channel (FLC) and the front right center audio channel (FRC)signal.

In this embodiment, to achieve the selective decoding of the bitstreaminto a predetermined number of audio channel signals, decoding levelinformation generated by a decoder may be used so that audio channelsignals are output based on the decoding levels. The decoding levelinformation may include the first decoding level dl0, which may be usedduring the selective decoding of the bitstream including two audiochannel signals into two audio channel signals, the second decodinglevel dl1, which may be used during the selective decoding of the twoaudio channel signals output at the first decoding level dl0 intosignals of the four audio channels L′, R′, C′, and C″, the thirddecoding level dl2, which may be used during the selective decoding ofthe L′ audio channel signal into the FL and BL audio channel signals,the R′ audio channel signal into the FR and BR audio channel signals,and the C″ audio channel signal into the C and LFE audio channelsignals, and the fourth decoding level dl3, which may be used during theselective decoding of the C′ channel signal into the FLC and FRC audiochannel signals.

In above embodiments, time domain temporal shaping (TP) and temporalenvelope shaping (TES) may be used to obtain intermediate outputs. Inaddition, each of the decoding levels may be greater than a tree depth.For example, MPEG surround data encoded in five channels may be decodedto be played back by 7 speakers that establish a tree structure.

In accordance with the above, a system, medium, and method of encodingsuch a multi-channel audio signal, according to an embodiment of presentinvention will now be further described. FIG. 14 illustrates amulti-channel audio signal encoding system, according to an embodimentof the present invention, and may include a first OTT encoder 1400, asecond OTT encoder 1410, a third OTT encoder 1420, a TTT encoder 1430, afourth OTT encoder 1440, and a bitstream generation unit 1450, forexample.

The first OTT encoder 1400 may generate a first OTT audio channel (L)signal and a first OTT parameter (also potentially called spaceinformation or spatial cues) that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a left front audio channel (LF) signal and a leftsurround audio channel (LS) signal. The second OTT encoder 1410 maygenerate a second OTT audio channel (R′) signal and a second OTTparameter that may include magnitude differences between thecorresponding channels and information about similarities between thecorresponding channels, using a right front audio channel (RF) signaland a right surround audio channel (RS) signal.

The third OTT encoder 1420 may generate a third OTT audio channel (C′)signal and a third OTT parameter that may include magnitude differencesbetween magnitudes of channels and information about similaritiesbetween the corresponding channels, using a center audio channel (C)signal and a woofer audio channel (LFE) signal. In addition, the TTTencoder 1430 may generate a TTT audio channel signal and a TTT parameterthat may include a magnitude difference between the correspondingchannels and information about similarities between the correspondingchannels, using the L′, R′, and C′ channel signals outputs by the first,second, and third OTT encoders 1400, 1410, and 1420, respectively.

The fourth OTT encoder 1440 may generate a fourth OTT audio channelsignal and a fourth OTT parameter that may include a magnitudedifference between the corresponding channels and information aboutsimilarities between the corresponding channels, using the TTT audiochannel signal output by the TTT encoder 1430. The bitstream generationunit 1450 may then compresses the OTT parameters produced by the firstthrough fourth OTT encoders 1440, 1410, 1420, and 1440, the TTTparameter produced by the TTT encoder 1430, and the audio signalproduced by the fourth OTT encoder 1440 so as to generate a bitstreamthat can be later decoded based upon such encoded audio signal and thecompressed parameter information.

FIG. 15 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention. In operation 1500,the first OTT parameter and the first OTT audio channel (L′) signal maybe generated from the left front audio channel (LF) signal and the leftsurround audio channel (LS) signal.

In operation 1510, the second OTT parameter and the second OTT audiochannel (R′) signal may be generated from the right front audio channel(RF) signal and the right surround audio channel (RS) signal.

In operation 1520, the third OTT parameter and the third OTT audiochannel (C′) signal may be generated from the center audio channel (C)signal and the woofer audio channel (LFE) signal.

In operation 1530, the TTT parameter and the TTT (stereo) audio channelsignal may further be generated from the L′, R′, and C′ channel signalsgenerated in operations 1500, 1510, and 1520, respectively.

In operation 1540, the fourth OTT parameter and the fourth OTT(downmixed-mono) audio channel signal may be generated from the stereoaudio channel signal generated in operation 1530.

In operation 1550, the parameters generated in operations 1500, 1510,1520, 1530, and 1540 and the mono-downmixed audio channel signalproduced in operation 1540 are compressed to generate the bitstream.

FIG. 16 illustrates a multi-channel audio signal encoding system,according to an embodiment of the present invention, which may include afirst OTT encoder 1600, a second OTT encoder 1610, a third OTT encoder1620, a fourth OTT encoder 1630, a fifth OTT encoder 1640, a TTT encoder1650, and a bitstream generation unit 1660, for example.

The first OTT encoder 1600 may generate a first OTT audio channel (FL′)signal and a first OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a front left audio channel (FL) signal and a front leftcenter audio channel (FLC) signal. The second OTT encoder 1610 maygenerate a second OTT audio channel (FR′) signal and a second OTTparameter that may include information about magnitude differences andsimilarities between the corresponding channels, using a front rightaudio channel (FR) signal and a front right center audio channel (FRC)signal. The third OTT encoder 1620 may further generate a third OTTaudio channel (L′) signal and a third OTT parameter that may includeinformation about magnitude differences and similarities between thecorresponding channels, using the FL′ audio channel signal produced bythe first OTT encoder 1600 and a back left audio channel (BL) signal.

The fourth OTT encoder 1630 may generate a fourth OTT audio channel (R′)signal and a fourth OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using the FR′ audio channel signal produced by the second OTTencoder 1630 and a back right audio channel (BR) signal. The fifth OTTencoder 1640 may generate a fifth OTT audio channel (C′) signal and afifth OTT parameter that may include information about magnitudedifferences and similarities between the corresponding channels, using acenter audio channel (C) signal and a woofer audio channel (LFE) signal.

The TTT encoder 1650 may generate a TTT audio channel signal and a TTTparameter that may include a difference between the magnitudes ofchannels and information about the similarities between thecorresponding channels, using the L′, R′, and C′ channel signals outputby the third, fourth, and fifth OTT encoders 1620, 1630, and 1640,respectively.

The bitstream generation unit 1660 may then compresses the parametersgenerated by the first through fifth OTT encoders 1600 through 1640 andthe TTT encoder 1650 and the TTT audio signal generated by the TTTencoder 1650 so as to produce a bitstream.

FIG. 17 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention. In operation 1700,the first OTT audio channel (FL′) signal and the first OTT parameter maybe generated from the FL audio channel signal and the FLC audio channelsignal. In operation 1710, the second OTT audio channel (FR′) signal andthe second OTT parameter may be generated from the FR audio channelsignal and the FRC audio channel signal.

In operation 1720, the third OTT audio channel (L′) signal and the thirdOTT parameter may be generated using the FL′ audio channel signalgenerated in operation 1700 and the BL audio channel signal. Further, inoperation 1730, the fourth OTT audio channel (R′) signal and the fourthOTT parameter may be generated from the FR′ audio channel signalgenerated in operation 1710 and the BR audio channel signal.

In operation 1740, the fifth OTT audio channel (C′) signal and the fifthOTT parameter may be generated from the C audio channel signal and theLFE audio channel signal. In operation 1750, the TTT (stereo) audiochannel signal and the TTT parameter may be generated from the L′, R′,and C′ channel signals produced in operations 1720, 1730, and 1740,respectively. In operation 1760, the parameters generated in operations1700, 1710, 1720, 1730, 1740, and 1750 and the stereo audio channelsignal generated in operation 1750 may then be compressed so as togenerate a corresponding bitstream.

FIG. 18 illustrates a multi-channel audio signal encoding system,according to an embodiment of the present invention, which may include afirst OTT encoder 1800, a second OTT encoder 1810, a third OTT encoder1820, a fourth OTT encoder 1830, a fifth OTT encoder 1840, a TTT encoder1850, and a bitstream generation unit 1860, for example.

The first OTT encoder 1800 may generate a first OTT audio channel (FC′)signal and a first OTT parameter that may include information aboutmagnitude differences and similarities between corresponding channels,using a front left center audio channel (FLC) signal and a front rightcenter audio channel (FRC) signal. The second OTT encoder 1810 maygenerate a second OTT audio channel (C″) signal and a second OTTparameter that may include a difference between the magnitudes ofcorresponding channels and information about similarities between thecorresponding channels, using the FC′ audio channel signal output by thefirst OTT encoder 1800 and a center audio channel (C) signal.

The third OTT encoder 1820 may generate a third OTT audio channel (L)signal and a third OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a front left audio channel (FL) signal and a back leftaudio channel (BL) signal. The fourth OTT encoder 1830 may generate afourth OTT audio channel (R′) signal and a fourth OTT parameter that mayinclude information about magnitude differences and similarities betweenthe corresponding channels, using an FR audio channel signal and a backright audio channel (BR) signal. The fifth OTT encoder 1840 may generatea fifth OTT audio channel (C′) signal and a fifth OTT parameter that mayinclude information about magnitude differences and similarities betweenthe corresponding channels, using the C″ audio channel signal output bythe second OTT encoder 1810 and a woofer audio channel (LFE) signal.

The TTT encoder 1850 may generate a TTT audio channel signal and a TTTparameter that may include information about magnitude differences andsimilarities between the corresponding channels, using the L′, R′, andC′ channel signals output by the third, fourth, and fifth OTT encoders1820, 1830, and 1840, respectively. The bitstream generation unit 1860may then compress the parameters generated by the first through fifthOTT encoders 1800 through 1840 and the TTT encoder 1850 and the TTTaudio channel signal generated by the TTT encoder 1850 so as to generatea bitstream.

FIG. 19 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention. In operation 1900,the first OTT audio channel (FC′) signal and the first OTT parameter maybe generated from the FLC audio channel signal and the FRC audio channelsignal. In operation 1910, the second OTT audio channel (C″) signal andthe second OTT parameter may be generated from the FC′ audio channelsignal produced in operation 1900 and the C audio channel signal. Inoperation 1920, the third OTT audio channel (L′) signal and the thirdOTT parameter may be generated from the FL audio channel signal and theBL audio channel signal.

In operation 1930, the fourth OTT audio channel (R′) signal and thefourth OTT parameter may be generated from the FR audio channel signaland the BR audio channel signal. In operation 1940, the fifth OTT audiochannel (C′) signal and the fifth OTT parameter may be generated fromthe C″ audio channel signal generated in operation 1910 and the LFEaudio channel signal. In operation 1950, the TTT (stereo) audio channelsignal and the TTT parameter may be generated from the L′, R′, and C′channel signals generated in operations 1920, 1930, and 1940,respectively. In operation 1960, the parameters generated in operations1900 through 1950 and the stereo audio channel signal generated inoperation 1950 may be compressed so as to generate a bitstream.

FIG. 20 illustrates a multi-channel audio signal encoding system,according to an embodiment of the present invention, which may include afirst OTT encoder 2000, a second OTT encoder 2010, a third OTT encoder2020, a fourth OTT encoder 2030, a fifth OTT encoder 2040, a sixth OTTencoder 2050, and a bitstream generation unit 2060, for example.

The first OTT encoder 2000 may generate a first OTT audio channel (C′)signal and a first OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a front left center audio channel (FLC) signal and afront right center audio channel (FRC) signal. The second OTT encoder2010 may generate a second OTT audio channel (L′) signal and a secondOTT parameter that may include information about magnitude differencesand similarities between the corresponding channels, using a front leftaudio channel (FL) signal and a back left audio channel (BL) signal. Thethird OTT encoder 2020 may generate a third OTT audio channel (R′)signal and a third OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a front right audio channel (FR) signal and a back rightaudio channel (BR) signal.

The fourth OTT encoder 2030 may generate a fourth OTT audio channel (C″)signal and a fourth OTT parameter that may include information aboutmagnitude differences and similarities between the correspondingchannels, using a center audio channel (C) signal and a woofer audiochannel (LFE) signal. The fifth OTT encoder 2040 may generate a fifthOTT audio channel signal and a fifth OTT parameter that may includeinformation about magnitude differences and similarities between thecorresponding channels, using the L′ audio channel signal output by thesecond OTT encoder 2010 and the C′ audio channel signal output by thefirst OTT encoder 2000. The sixth OTT encoder 2050 may generate a sixthOTT audio channel signal and a sixth OTT parameter that may includeinformation about magnitude differences and similarities between thecorresponding channels, using the R′ audio channel signal output by thethird OTT encoders 2020 and the C″ audio channel signal output by thefourth OTT encoder 2030.

The bitstream generation unit 2060 may then compress the parametersgenerated by the first through sixth OTT encoders 2000 through 2050, thefifth OTT audio channel signal generated by the fifth OTT encoder 2040,and the sixth OTT audio channel signal generated by the sixth OTTencoder 2060, so as to generate a bitstream.

FIG. 21 illustrates a multi-channel audio signal encoding method,according to an embodiment of the present invention. In operation 2100,the first OTT audio channel (C′) signal and the first OTT parameter maybe generated from the FLC audio channel signal and the FRC audio channelsignal. In operation 2110, the second OTT audio channel (L′) signal andthe second OTT parameter may be generated from the FL audio channelsignal and the BL audio channel signal. In operation 2120, the third OTTaudio channel (R′) signal and the third OTT parameter may be generatedfrom the FR audio channel signal and the BR audio channel signal. Inoperation 2130, the fourth OTT audio channel (C′) signal and the fourthOTT parameter may be generated from the C audio channel signal and theLFE audio channel signal.

In operation 2140, the fifth OTT audio channel signal and the fifth OTTparameter may be generated from the L′ audio channel signal generated inoperation 2110 and the C′ audio channel signal generated in operation2100. In operation 2150, the sixth OTT (stereo) audio channel signal andthe sixth OTT parameter may be generated from the R′ audio channelsignal produced in operation 2120 and the C″ audio channel signalgenerated in operation 2130. In operation 2160, the parameters generatedin operations 2100 through 2140, the fifth OTT audio channel signalgenerated in operation 2140, and the stereo audio channel signalgenerated in operation 2150 may be compressed to generate a bitstream.

In a system, medium, and method of encoding/decoding a multi-channelaudio signal, according to an embodiment of the present invention, evena single input bitstream can be decoded into audio channel signals of asuitable number of channels based on the type of a speaker configurationused and/or decoding level information. Thus, scalable channel decodingcan be achieved by partially and selectively decoding an inputbitstream. In such scalable channel decoding, a decoder may set decodinglevels and output audio channel signals based on the decoding levels,thereby decreasing decoding complexity.

In addition to the above described embodiments, embodiments of thepresent invention can also be implemented through computer readablecode/instructions in/on a medium, e.g., a computer readable medium, tocontrol at least one processing element to implement any above describedembodiment. The medium can correspond to any medium/media permitting thestoring and/or transmission of the computer readable code.

The computer readable code can be recorded/transferred on a medium in avariety of ways, with examples of the medium including magnetic storagemedia (e.g., ROM, floppy disks, hard disks, etc.), optical recordingmedia (e.g., CD-ROMs, or DVDs), and storage/transmission media such ascarrier waves, as well as through the Internet, for example. Here, themedium may further be a signal, such as a resultant signal or bitstream,according to embodiments of the present invention. The media may also bea distributed network, so that the computer readable code isstored/transferred and executed in a distributed fashion. Still further,as only an example, the processing element could include a processor ora computer processor, and processing elements may be distributed and/orincluded in a single device.

In addition to the above, though embodiments have been explained in viewof systems, the corresponding embodiments can equally be implemented inapparatuses.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A multi-channel audio signal decoding method,comprising: decoding two audio channel signals using two-to-three (TTT)spatial information into first, second and third channel signals;decoding the first channel signal using first one-to-two (OTT) spatialinformation into first plural channel signals; decoding the secondchannel signal using second OTT spatial information into second pluralchannel signals; decoding the third channel signal using third OTTspatial information into third plural channel signals; decoding one ofthe first plural channel signals using fourth OTT spatial informationinto fourth plural channel signals; and decoding one of the secondplural channel signals using fifth OTT spatial information into fifthplural channel signals.
 2. The method of claim 1, wherein the spatialinformation comprises information of magnitude differences orsimilarities between corresponding channels.
 3. The method of claim 1,wherein: the first, second, and third channel signals correspond to aleft audio channel L′, a right audio channel R′, and a center audiochannel C′, respectively; the first plural channel signals correspond toa front left audio channel FL′ and a back left audio channel BL,respectively; the second plural channel signals correspond to a frontright audio channel FR′ and a back right audio channel BR, respectively;the third plural channel signals correspond to a center audio channel C″and an LFE audio channel, respectively; the fourth plural channelsignals correspond to a front left audio channel FL and a front leftcenter audio channel FLC, respectively; and the fifth plural channelsignals correspond to a front right audio channel FR and a front rightcenter audio channel FRC, respectively.
 4. The method of claim 1,wherein the method is performed by selectively decoding the bitstreambased on decoding levels of the OTT decoding operations and selectivedecoding of the three audio channel signals, respectively.